It is known in the art to use an apparatus to enhance the visual appearance of the veins in a patient to facilitate insertion of needles into the veins. An example of such a system is described in U.S. Pat. Nos. 5,969,754 and 6,556,858incorporated herein by reference as well as a publication entitled “The Clinical Evaluation of Vein Contrast Enhancement”. Luminetx is currently marketing such a device under the name “Veinviewer Imaging System” and information related thereto is available on its website, which is incorporated herein by reference.
The Luminetx Vein Contrast Enhancer (hereinafter referred to as LVCE) utilizes an infrared light source for flooding the region to be enhanced with infrared light generated by an array of LEDs. A CCD imager is then used to capture an image of the infrared light reflected off the patient. The resulting captured image is then projected by a visible light projector onto the patient in a position closely aligned with the image capture system. Given that the CCD imager and the image projector are both two dimensional, and do not occupy the same point in space, it is relatively difficult to design and build a system that closely aligns the captured image and the projected image.
A further characteristic of the LVCE is that both the imaging CCD and the projector have fixed focal lengths. Accordingly, the patient must be at a relatively fixed distance relative to the LVCE. This necessitates that the LVCE be positioned at a fixed distance from the region of the patient to be enhanced.
The combination of the size of the LVCE and the fixed focal arrangement precludes using the LVCE as small portable units that are hand held.